In the semiconductor electronics industry, various semiconductor devices are packaged in standard electronic device packages. One such standard package is referred to as a "flat pack". The flat pack electronic device package comprises an enclosed housing, usually rectangular, containing a semiconductor device and having one or more rows of relatively thin, flexible ribbon leads extending laterally from one or more side edges of the housing. The ribbon leads of the flat pack are adapted to be soldered to preformed locations on the surface of the printed circuit board to reduce the overall height of the printed circuit board and for other reasons.
Due to the fragile nature of the ribbon leads on a flat pack electronic device package, as well as a desire to protect the housing and the semiconductor device itself, flat packs are commonly stored and transported on plastic bodies called carriers. As shown in FIGS. 1 and 2, a typical carrier 10 receives the housing of a flat pack (not shown) in close confinement with cavity 14. Each of the ribbon leads (not shown) extending from the housing are received within one of the parallel channels 16 defined by teeth 18 and communicating with the cavity 14. Although not shown, fingers or clips may be mounted on the carrier to grip the flat pack housing and retain it within the cavity. The carrier defines three indentations 12 along its longitudinal edges. The asymmetrical arrangement of these indentations enables the carrier to be oriented by automatic machinery for loading or unloading onto storage or handling structures. The underside of the carrier also includes a pair of laterally spaced, longitudinal ribs 20 which space the carrier and flat pack above any surface on which the carrier is placed.
It is desirable to test all or a predetermined percentage of semiconductor devices during manufacturing operations. Standard testing procedures include mounting a plurality of semiconductor devices on a test board, known as a burn-in board, and simultaneously subjecting the devices to various environmental and electrical stresses while mounted on the burn-in board. The devices are then removed from the burn-in board and electronically tested in one or more test fixtures. Those devices failing the functional tests are discarded or classified according to test performance.
Since it is desirable to test all or a large portion of the production output from a manufacturing line for semiconductor devices, it is also desirable that the loading and unloading of the electronic device packages with respect to the various test equipment be accomplished as rapidly and economically as possible. The electronic device packages, of whatever type, may be loaded and unloaded by hand from the test fixtures. This method, however, is extremely time-consuming and therefore expensive. It is preferable to utilize automatic handling arrangements such as robotics, to insert or remove the electronic device packages from the various test equipment.
Semiconductor devices, even when mounted in packages, must be handled carefully to avoid damage to the devices or to the package. For instance, the ribbon leads on the flat pack type package are relatively fragile and easily torn if subjected to excessive forces. The housing of a flat pack may also be damaged, and even the semiconductor device contained in the housing may also be damaged, if not handled carefully. Unfortunately, conventional techniques involving manual handling of the electronic device packages produce an undesirably high rate of damage to flat pack electronic device packages. Frequent insertion and removal of the electronic device package from sockets or other test fixtures also exposes the electronic device package and its ribbon leads to destructive forces.
Sockets have been developed which reduce or eliminate the force required to load or unload a flat pack electronic device package from the socket. Typically conventional flat pack type sockets include a base portion having a plurality of electrically conductive contacts mounted therein. A structure is provided mounted on the base portion for securing the flat pack electronic device package to the base portion with all of the ribbon leads aligned and in contact with one of the socket contacts on the base portion. Such sockets reduce the damage rate but still suffer from several limitations and inefficiencies. For instance, it is still necessary with conventional devices to manually align, load and unload the flat pack on a carrier with the socket. Some conventional sockets require that the flat pack electronic device package be removed from its protective carrier for loading into the socket. Further, conventional flat pack socket designs sometimes secure the flat pack to the socket by applying a force directly to the flat pack housing or the carrier bearing the flat pack. As previously discussed, this is undesirable and leads to damage to the flat pack and/or carrier.
Another problem associated with conventional flat pack sockets is that of making a conductive connection with each of the ribbon leads of that flat pack. If the force applied to the ribbon leads by the socket contacts is excessive, the ribbon contacts may be damaged or destroyed. For instance, some conventional flat pack sockets employ wire type contacts. Wire type contacts apply all the force to a relatively narrow portion of the ribbon lead, thereby tending to deform or damage the ribbon lead.
Mounting conventional flat pack sockets on a printed circuit board (such as a burn-in board or test fixture) or the like poses a particular problem. Typically, this is accomplished by soldering mounting tabs or the leads projecting from the bottom of the socket into a like number of preformed aligned holes in a printed circuit board or the like. Typically the holes are arranged in parallel rows on the printed circuit board. However, depending on the nature of the semiconductor device to be tested, the test equipment to be used and the test procedure to be followed, some of the holes in each row are unnecessary and therefore omitted. Consequently, each of the leads mounted in the socket must conform to the appropriate hole pattern in the printed circuit board or the like. Thus, each socket must be uniquely configured for a specific application and a variety of leads must be constructed and utilized in the socket in the correct sequence, all of which increases assembly and manufacturing costs.